Rehydrate shiitake mushrooms in warm water a few hours before cooking.
Once the mushrooms have softened, remove the hard stems and discard. Julienne the mushroom caps and set aside.
Fill a steamer with water and place on the stovetop over medium heat.
In a bowl or a pie plate, crack all five eggs and whisk thoroughly to break yolks and hard whites. Season with salt.
Add water to the eggs and gently mix until fully incorporated. There should be no streaks and the liquid should be a pale yellow.
Evenly sprinkle the julienne shiitakes onto the plate and add the sesame oil.
Place the plate into the steamer and cover.
Return steamer to a low simmer and set a timer for 8 minutes. Check the steamer after 4 minutes. Turn down heat if the eggs begin to bubble around the edges. The eggs are done cooking when a gentle shake of the pan makes the eggs quiver. The eggs should be a smooth, silky texture.
Turn off the heat and leave the eggs covered for an additional 5 minutes.
Add the green onion and cilantro (optional). Serve with hot rice and season with soy sauce.